Musical instrument amplifier



FIG. 1 is a perspective view of a musical instrument amplifier showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof; the left side elevational view being a mirror image thereof; and,

FIG. 4 is a top plan view thereof.

The rear elevational view and the bottom plan view are unornamented and form no part of the claimed design. 

The ornamental design for a musical instrument amplifier, as shown and described. 